kmathern wrote:In about:plugins is any other plugin (other than "VLC Web Plugin") shown for mp3?

M12 might have come with some other plugin preinstalled, but I don't recall what it was.

No, the VLC plugin is the only one that names mp3s.

From the comments that everyone seems to be able to play the link, I am starting to think I might have, at some point, removed something (a library perhaps) that caused this mess. I would guess this happened when I upgraded my iceweasel, but can't be sure.

@JBoman, how can I check whether the issue is conflicting plugins? Just trial and error?

As a test, I removed all the media plugins from firefox-28.0, and was still able to play the stream. I believe that Firefox now ships with mp3 and h.264 support by default. After some research, it appears that it's using the system gstreamer libraries to do so. To disable gstreamer, check the media.gstreamer.enabled in the about:config, set it to False.

Stevo wrote:As a test, I removed all the media plugins from firefox-28.0, and was still able to play the stream. I believe that Firefox now ships with mp3 and h.264 support by default. After some research, it appears that it's using the system gstreamer libraries to do so. To disable gstreamer, check the media.gstreamer.enabled in the about:config, set it to False.

Stevo's fix worked! I set media.gstreamer.enabled to false on about:config and audio works perfectly again!

So this was, then, an issue of conflicting plugins or what? (just to be clear)

It just may be the vlc plugin that causes the problem--I have mine set to true and had gecko-mediaplayer installed, and did not have any issues. Though I have also installed the old mediaplayerconnectivity extension so I can watch non-Flash streams in a VLC window if I want--then I can hit the Record button if I want to record part of a stream that gets interesting.